Polybutadiene or BR rubber and butadiene-styrene block polymers are widely used in the styrene polymer industry to produce high-impact polystyrene (HIPS) and acrylonitrile-butadiene-styrene copolymer (ABS). It is known that a higher degree of grafting level of styrene onto the rubber results in better properties of the HIPS. There is, accordingly, a continuing need for preparing improved high impact polymeric compositions.